This invention relates to an improved filling tube and seal construction for inflatable implants and more particularly to a filling tube and seal construction for use in inflatable implants used in breast reconstruction. However, it will be understood that this invention may be useful in other types of inflatable implants where it is desired to insure against leakage after implantation and inflation.
Inflatable implants such as those used in breast reconstruction include at least one, and sometimes two soft and pliable members or lumens. The lumens are adapted to be filled with various materials including liquids such as saline, silicone gel, and sometimes both. For example, in my co-pending application Ser. No. 693,890, filed Jan. 23, 1985, and entitled Improved Implant and Inflating Construction, there is disclosed a double lumen implant wherein the outer chamber contains a silicone gel. The inner lumen is filled with a saline solution to inflate the implant to the desired volume. The membranes are unattached from one another, and this, together with the outer viscous gel layer, gives the implant a natural appearance and feel.
The gel in the outer chamber is in contact with both valves thus facilitating seal of the valves when a filling tube has penetrated both valves for an extended period of time (up to three to six months). When the filling tube is removed after such a long period of time, the valves may remain in a distended condition due to stretch caused by the filling tube. Migration of gel between the partially opened valve leaves or flaps is thus of importance in valve closure.
An important feature of these devices resides in the valve used in inflating the implant. One type uses a filling tube which is passed through a valve opening in the membrane to enable delivery of inflating fluid to the membrane interior. In the case of the double membrane implant discussed above, the filling tube passes through valve openings in both membranes and delivers the inflating fluid (saline solution) to the chamber in the inner membrane. Upon completion of the inflation process, the filling tube is withdrawn from both valves. Importantly, the valves reseal upon removal of the filling tube to prevent escape of the fluid.
The valves referred to above are formed in the membranes and are and remain a part of the membrane after the filling sequence is completed. For obvious reasons, e.g., patient comfort, these valves should be small and, as much as possible, be constructed of relatively soft material. However, it is also important that the valve safely and effectively reseal once the filling tube has been withdrawn to prevent loss of fluid from the membrane.
Such valves when constructed of a relatively soft and pliable material satisfy the need that they be comfortable for the patient. However, this can give rise to another problem if the filling tube remains in place for a relatively long period of time, sometimes for several weeks during inflation. In such cases, the valve material may lose its memory and acquire a "set," and therefore not recover its original shape when the filling tube is removed. Also, these implants are often packaged with the filling tube in place in the valve so that there is a higher likelihood of valve leakage because of the sometimes long shelf life of the implant. Thus, there can be a relatively high incidence of leakage in these valves.
In my co-pending application referred to above, the viscosity of the gel material in the chamber between the outer and inner lumens generally is sufficient to insure that gel does not escape the valve in the outer lumen. Sealing of the valve in the inner lumen is also assisted to some extent by the gel. However, the saline solution in the inner chamber is much less viscous than the silicone gel and can leak past the inner valve into the outer chamber if the inner valve does not reseal. In some cases, saline solution entering the outer chamber can leak past the outer valve and escape the implant. In either case, there is a need for a valve for use in this type environment which is soft and pliable and, therefore, comfortable for a patient, and which functions to effectively reseal after removal of an instrument such as a filling tube which has remained in place therein for a relatively long period of time.
In another of my co-pending applications, Ser. No. 06/800,211, filed Nov. 21, 1985, and entitled "Filling Tube Valve Construction for Inflatable Implants." I disclose an improved valve construction. In that application, the valve comprises a length of relatively flexible material having a passage therethrough and joined to the lumen around the inlet opening. The flexible material extends inwardly into the lumen and is normally biased toward a smooth curved configuration which causes the valve passage to close. The valve passage is opened by inserting a filling tube through the passage causing the flexible material to straighten. The flexible material returns to its original curved configuration upon removal of the tube whereupon the valve passage recloses.
The aforementioned valve works well, is useful in both single and multiple lumen prosthesis, adds minimally to the cost of the prosthesis, does not adversely affect the comfort of the patient and aids in preventing leakage.
However, it is presently believed that my new filling tube and seal construction will provide an improved seal over the aforementioned device and will have most, if not all, of the advantage of that device.